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Multidetector computed tomography sizing of bioprosthetic valves: guidelines for measurement and implications for
R Rajani1, R Attia2, F Condemi2
1Department of Cardiac Computed Tomography, Guy's and St Thomas' NHS Foundation Trust, London SE1 7EH, UK; Cardiovascular Division and Division of Imaging Sciences and Biomedical Engineering, King's College London British Heart Foundation Centre of Excellence, National Institute of Health Research Biomedical Research Centre at Guy's and St Thomas' NHS Foundation Trust, London SE1 7EH, UK.
Aim:
To describe a technique for bioprosthetic multidetector computed tomography (MDCT) sizing and to compare MDCT-derived values against manufacturer-provided sizing.
Materials And Methods:
Fourteen bioprosthetic stented valves commonly used in the aortic valve position were evaluated using a Philips 256 MDCT system. All valves were scanned using a dedicated cardiac CT protocol with a four-channel electrocardiography (ECG) simulator. Measurements were made of major and minor axes and the area and perimeter of the internal stent using varying reconstruction kernels and window settings. Measurements derived from MDCT (MDCT ID) were compared against the stent internal diameter (Stent ID) as provided by the valve manufacturer and the True ID (Stent ID + insertion of leaflets). All data were collected and analysed using SPSS for Mac (version 21).
Results:
The mean difference between the MDCT ID and Stent ID was 0.6±1.9 mm (r=0.649, p=0.012) and between MDCT ID and True ID 2.1±2 mm (r=0.71, p=0.005). There was no difference in the major (p=0.90), minor (p=0.87), area (p=0.92), or perimeter (p=0.92) measurements when sharp, standard, and detailed stent kernels were used. Similarly, the measurements remained consistent across differing windowing levels.
Conclusion:
Bioprosthetic stented valves may be reliably sized using MDCT in patients requiring valve-in-valve (VIV) interventions where the valve type and size are unknown. In these cases, clinicians should be aware that MDCT has a tendency to overestimate the True ID size.
